The Rock Cycle

1. The Rock Cycle • Rocks are any solid mass of mineral or mineral-like matter that occurs naturally on Earth.

2. Types of Rocks • 3 types of interactions with Earth’s water, land, and air • Metamorphic –heat and pressure • Igneous – cooling and solidification of lava • Sedimentary – compaction and cementation of sediments

3. The Rock Cycle (cont’d) • The rock cycle does not always occur in a specific order. • Igneous rocks (Step 2) can directly become metamorphic rocks (Step 5).

4. The Work of Streams • Erosion – water causes loose particles to be moved through abrasion, grinding, or by dissolving soluble material. • Sediment Transport – sediments are moved by the rivers and streams • In solution (dissolved load) • In suspension (suspended load) • Scooting or rolling along the bottom (bed load)

5. Deposition • The settling of particles from the river is known as deposition. • Structures that form due to deposition • Deltas • Natural Levees

6. Weathering of Rocks • 2 main types of weathering to rocks • Mechanical weathering requires physical forces to break rocks into smaller pieces. • Chemical weathering requires the transformation of rock into one or more new compounds.

7. Mechanical Weathering – Frost Wedging • water forces its way into the cracks • water freezes which causes the crack to expand • more water fills the cracks & freezes • rocks split apart

8. Mechanical Weathering – Biological Activity • plants & animals burrow through the rock • humans blast rocks apart looking for minerals & deforestation • dead organisms produce acids that dissolves the rock

9. Chemical Weathering – Water • Most important agent of chemical weathering • dissolves various gases from the atmosphere and soil • causes a reaction with minerals in the rocks • Oxygen reacts with the metals in the rocks to produce oxide (rust) to create a yellow to reddish-brown rocks • Acids dissolve away the surface of the rocks

10. Longshore Current and Transport • Longshore Current – the movement of water parallel to the shoreline.

11. Longshore Current and Transport • Longshore Transport – the movement of sand along the beach.

12. Human Impacts • Seawall – designed to absorb power of incoming waves and tides and halt the retreat of a shoreline. • Works to save property behind the wall. • Causes the sediments in front of the wall to be swept in the ocean. • Further loss of beach prompts people to build a bigger, “better” wall to stop the erosion caused by the original seawall.

13. Human Impacts • Breakwater • A wall built in the ocean to reduce the size of waves. More useful for protecting boats than preventing erosion.

14. Human Impacts • Groins – designed to trap sediments in an area of the beach. • disrupt the longshore transport • the beach on the other side of the groin will continue to loose sediments

15. Human Impacts • Beach Nourishment –adding sediment from another beach, offshore bar, island or inland area to increase the size of the beach. • Adding the wrong type can disrupt the natural processes. • The sediments may be contaminated with pollutants.

16. Soil • 4 major components • Mineral matter – 45% • Organic matter (humus) – 5% • Water – 25% • Air – 25% • Soil texture - type and amount of different soils found in the soil. • texture determines how well the soil can grow crops

17. Soil Formation • Parent Material – the rock that is below the soil is broken-down. • Time – increase in time  increase in the amount of soil and thickness of the layer • Climate – • wetter, hotter climates will break-down parent material quicker • Drier, colder climates will take the longest

18. Soil Formation(cont’d) • Plants and burrowing animals – create soil faster by leaving larger amounts of organic material • Slope – steep slopes tend to have less soil • less water and less plants • mountain slopes that face the sun tend to have more soil